Evaluation of different dispatching rules in computer integrated manufacturing using design of experiment techniques

This research is based on the study of process planning and scheduling in job shop flexible manufacturing systems. This project need to evaluate planning algorithms, determine appropriate algorithms and suggest better algorithm as a tool to optimize the process planning. Extensive computational experiments are carried out to verify the efficiency of our algorithm using OpenCIM software. By using the OpenCIM simulation software, the evalution of planning algorithms were carried out base on different scheduling algorithms such as First In First Out (FIFO), Shortest Processing Time (SPT), and Maximum Priority. The target of this study is to evaluate the performance of selected dispatching rules for different operation on the existing Computer Integrated Manufacturing (CIM) facility using a simulation model against different performance measures and to compare the results with the literature. Three factors with three levels of severity along with 3 different scheduling dispatching rules, a 3 x 3 x 3 = 27 full factorial Design of Experiment (DOE) set-up were used to evaluated the performance of the system under study. Analysis of variance (AVONA) was used to identify the interactions between factors. Three performance measures, Total Run Time, Maximum Queue Length and Machine Efficiency were used in the experiments. The system performance depended on Machine Efficiency when the number of released parts is maximum and the number of priority is minimum. Furthermore, considering the maximum queue length, the system performs much better when the selected dispatching rule is either MAX PRIORITY or SPT with number of priority is one and number of part release is eight. The system’s total run time performs markedly better when the number of released parts is set at eight or higher. It was concluded that the overall best simple dispatching rules among all other simple rules in order of their performance are Shortest Processing Time (SPT), Maximum Priority, First In First Out (FIFO)

Scheduling of a computer integrated manufacturing system: a simulation study

Purpose: The purpose of this paper is to study the effect of selected scheduling dispatching rules on the performance of an actual CIM system using different performance measures and to compare the results with the literature. Design/methodology/approach: To achieve this objective, a computer simulation model of the existing CIM system is developed to test the performance of different scheduling rules with respect to mean flow time, machine efficiency and total run time as performance measures. Findings: Results suggest that the system performs much better considering the machine efficiency when the initial number of parts released is maximum and the buffer size is minimum. Furthermore, considering the average flow time, the system performs much better when the selected dispatching rule is either Earliest Due Date (EDD) or Shortest Process Time (SPT) with buffer size of five and the initial number of parts released of eight. Research limitations/implications: In this research, some limitations are: a limited number of factors and levels were considered for the experiment set-up; however the flexibility of the model allows experimenting with additional factors and levels. In the simulation experiments of this research, three scheduling dispatching rules (First In/First Out (FIFO), EDD, SPT) were used. In future research, the effect of other dispatching rules on the system performance can be compared. Some assumptions can be relaxed in future work. Practical implications: This research helps to identify the potential effect of a selected number of dispatching rules and two other factors, the number of buffers and initial number of parts released, on the performance of the existing CIM systems with different part types where the machines are the major resource constraints. Originality/value: This research is among the few to study the effect of the dispatching rules on the performance of the CIM systems with use of terminating simulation analysis. This is also significant given the nature of the CIM systems that are mostly used to produce different parts in varying quantities and thus do not produce parts on a continuing basis. This research is amongst the first to study the combined effect of dispatching rule and the buffer size in the CIM systems where the job arrivals are predetermined and depend on the completion of the existing parts in the system. A description of how buffer size and initial part release is related to the performance of the CIM system under study for the studied priority dispatching rule is also provided.Peer Reviewe

Task Allocation Strategies in Multi-Robot Environment

Multirobot systems (MRS) hold the promise of improved performance and increased fault tolerance for large-scale problems. A robot team can accomplish a given task more quickly than a single agent by executing them concurrently. A team can also make effective use of specialists designed for a single purpose rather than requiring that a single robot be a generalist. Multirobot coordination, however, is a complex problem. An empirical study is described in the thesis that sought general guidelines for task allocation strategies. Different strategies are identified, and demonstrated in the multi-robot environment.Robot selection is one of the critical issues in the design of robotic workcells. Robot selection for an application is generally done based on experience, intuition and at most using the kinematic considerations like workspace, manipulability, etc. This problem has become more difficult in recent years due to increasing complexity, available features, and facilities offered by different robotic products. A systematic procedure is developed for selection of robot manipulators based on their different pertinent attributes. The robot selection procedure allows rapid convergence from a very large number of candidate robots to a manageable shortlist of potentially suitable robots. Subsequently, the selection procedure proceeds to rank the alternatives in the shortlist by employing different attributes based specification methods. This is an attempt to create exhaustive procedure by identifying maximum possible number of attributes for robot manipulators.Availability of large number of robot configurations has made the robot workcell designers think over the issue of selecting the most suitable one for a given set of operations. The process of selection of the appropriate kind of robot must consider the various attributes of the robot manipulator in conjunction with the requirement of the various operations for accomplishing the task. The present work is an attempt to develop a systematic procedure for selection of robot based on an integrated model encompassing the manipulator attributes and manipulator requirements

Design of a Generic Manufacturing Cell Control System.

The feasibility of design and demonstration of a cell control system to function in the fully integrated manufacturing environment independent of the parts produced or the manufacturing processes involved was investigated. A hierarchical control structure was used. Free standing implementations of a cell controller, a workstation controller, and programmable device interfaces were designed. The system is data driven, and was designed to use the manufacturing databases that exist in the computer integrated manufacturing environment. Operation of the cell controller and its interaction with the rest of the system was demonstrated in real-time by simulating the computer integrated manufacturing environment on microcomputers connected to each other via communication links

Uses and applications of artificial intelligence in manufacturing

The purpose of the THESIS is to provide engineers and personnels with a overview of the concepts that underline Artificial Intelligence and Expert Systems. Artificial Intelligence is concerned with the developments of theories and techniques required to provide a computational engine with the abilities to perceive, think and act, in an intelligent manner in a complex environment. Expert system is branch of Artificial Intelligence where the methods of reasoning emulate those of human experts. Artificial Intelligence derives it\u27s power from its ability to represent complex forms of knowledge, some of it common sense, heuristic and symbolic, and the ability to apply the knowledge in searching for solutions. The Thesis will review : The components of an intelligent system, The basics of knowledge representation, Search based problem solving methods, Expert system technologies, Uses and applications of AI in various manufacturing areas like Design, Process Planning, Production Management, Energy Management, Quality Assurance, Manufacturing Simulation, Robotics, Machine Vision etc. Prime objectives of the Thesis are to understand the basic concepts underlying Artificial Intelligence and be able to identify where the technology may be applied in the field of Manufacturing Engineering

A Manufacturing Execution System using Siemens\u27 PC Based Automation Technology

The focus of any manufacturing operation is to establish better yields, reduced cycle times, increase quality, and handle dynamic demand/resource fluctuations. Over the past few years many manufacturing companies have implemented Enterprise Resource Planning (ERP) systems and they have proved themselves to be successful in achieving these goals. However, real-time data is required in order to portray an accurate account of the day-to-day and/or hourly product manufacturing operations. Retrieval of this real-lime data is a challenging task. A Manufacturing Execution System (MES) is a real-time information system that improves the performance of the shop floor operations by linking business planning, order entry, material management, purchasing and accounting to the controls on the factory equipment. Siemens\u27 PC-based automation technology is an emerging technology that appears to provide a robust architecture for integrating all elements of the manufacturing environment. Applications that range from simple control to distributed control and full-fledged MES can be developed using Siemens\u27 architecture. The primary focus of this thesis is applied research to facilitate the development of a Manufacturing Execution System to control a flexible manufacturing system, CAMCELL, using Siemens\u27 PC-based automation technology and Microsoft\u27s database technology. CAMCELL contains two CNC machining centers, assembly robots, and a vision system, all of which are interlinked by a material handling system. The software architecture of the CAMCELL is based on NIST\u27s five level hierarchy. Specifically, it contains functional modules for order entry, scheduling, and routing. In addition to these functional modules, there are various support modules. In this study, we have developed software architecture to achieve vertical integration of the process control layer, the MES layer and the ERP layer. Using Siemens\u27 WinCC software, real-time process data was collected and integrated into an MES database. The study demonstrates how order information stored in a high-level database is converted into useful information for the control layer. The study also demonstrates the ability of WinCC and Visual FoxPro to update the production data into the MES database. Various Operator interface and database screens are proposed for CAMCELL